[petsc-dev] Current status: GPUs for PETSc

[Matthew Knepley]

On Mon, Nov 5, 2012 at 6:27 AM, Lawrence Mitchell <
lawrence.mitchell at ed.ac.uk> wrote:

> Hi Karli, and others,
>
> On 05/11/2012 01:51, Karl Rupp wrote:
>
> ...
>
> > That's it for now, after some more refining I'll start with a careful
> > migration of the code/concepts into PETSc. Comments are, of course,
> > always welcome.
>
> So we're working on FE assembly + solve on GPUs using fenics kernels
> (github.com/OP2/PyOP2).  For the GPU solve, it would be nice if we could
> backdoor assembled matrices straight on to the GPU.  That is, create a Mat
> saying "this is the sparsity pattern" and then, rather than calling
> MatSetValues on the host, just pass a pointer to the device data.
>

Yes, I was doing the same thing. GPU assembly is not really any faster than
CPU,
so I did not publish it, but not having to transfer the values back is very
nice.

In Karl's scheme its easy, since you just go in and get the device pointer
from the
handle. We can talk about a user level interface after you verify that this
works and
is what you want.

    Matt


> At the moment, we're doing a similar thing using CUSP, but are looking at
> doing multi-GPU assembly + solve and would like not to have to reinvent too
> many wheels, in particular, the MPI-parallel layer.  Additionally, we're
> already using PETSc for the CPU-side linear algebra so it would be nice to
> use the same interface everywhere.
>
> I guess effectively we'd like something like MatCreateSeqAIJWithArrays and
> MatCreateMPIAIJWithSplitArrays but with the ability to pass device pointers
> rather than host pointers.  Is there any roadmap in PETSc for this kind of
> thing?  Would patches in this direction be welcome?
>
> Cheers,
> Lawrence
>
> --
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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